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int2.java
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71 lines (58 loc) · 1.99 KB
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public class int2 {
public static int[] sub_arr (int[] arr) {
// base case
if (arr == null || arr.length < 1) return null;
// mLoc = max (n, n+mLoc)
// mGl = max (mLoc, mGl)
// start_i: if n > n+prev mL
// end_i for subarray: if new mL > old MG
int mLoc = arr[0];
int mGl = arr[0];
int start_i = 0;
int end_i = 0;
for (int i = 1; i < arr.length; i++) {
int n = arr[i];
int old_mGl = mGl;
if (n > mLoc + n) start_i = i;
mLoc = Math.max(n, n + mLoc);
mGl = Math.max(mLoc, mGl);
if (mLoc > old_mGl) end_i = i;
}
System.out.println("start: " + start_i);
System.out.println("end: " + end_i);
// create sub_arr; {0,1,2}; start=4, end=6
int sa_len = end_i - start_i + 1; // 3
int[] sub_arr = new int[sa_len];
for (int i = 0; i < sa_len; i++) {
sub_arr[i] = arr[start_i];
System.out.println("sub_arr elem: " + sub_arr[i]);
start_i++;
}
// int[] sub_arr_res = {1, 2, 3};
return sub_arr;
}
public static void main(String[] args) {
int[] arr = {1,2,3,-5,0,1,2};
int[] sub_arr_out = sub_arr(arr);
for (int i = 0; i < sub_arr_out.length; i++) {
System.out.print(sub_arr_out[i]);
if (i < sub_arr_out.length - 1) {
System.out.print(",");
}
}
}
}
/*
* given array of integers, find the subarray with greatest sum
* return subarray
* pos int, 0, neg int
* {1,2,3,-5,0,1,2} => {1,2,3}
* i=0,n=1,mL=1,mG=1
* i=1,n=2,mL=2 or 2+1=3,mG=3 : n !> mL[-1]+n, do not start+; new mL > old mGl, end++
* i=2,n=3,mL=3 or 3+3=6,mG=6 : n !>= mL[-1]+n, do not start+; new ml > old mGl, end++
* i=3,n=-5,mL=-5 or -5+6=1,mG=6 : !start++, end++
* mLoc = max (n, n+mLoc)
* mGl = max (mLoc, mGl)
* start_i, end_i for subarray
* return a subarr[starti . . . endi]
*/